Given the evidence that Duane syndrome (DS) results from an absence of the abducens nerve (cranial nerve VI) and aberrant innervation, and that it is associated with other anomalies in some cases, it is thought to result from a disturbance of normal embryonic development by either a genetic or an environmental factor at the time when the cranial nerves and ocular muscles are developing (between the third and sixth week of pregnancy). Genetic studies of two large families with DS inherited autosomal dominantly (without associated abnormalities) established that mutations in the CHN1 gene were found to be the cause in these and several other families.
Duane-radial ray syndrome (DRRS), inherited in an autosomal dominant manner, has been shown to be caused by mutations in the SALL4 gene. However, no SALL4 gene mutations were found in 25 sporadic cases of isolated DS (occurring in one individual in a family with no additional abnormalities).
DS can also be found as part of another complex autosomal recessive disorder (that can include deafness, facial weakness, vascular malformations and leaning difficulties) due to mutations in the HOXA1 gene. In addition, chromosome studies of individuals with DS and other abnormalities have, in rare cases, shown abnormalities that suggest other locations for genes responsible for causing DS.
Last updated: 3/21/2012
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